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Re: The Harbor Master Called me Today

Originally Posted by Favorite

You woke up my curiosity cat. Can you explain what you are checking ? My vague understanding of battery chargers is that they are a 120v - 15v transformer, follwed by a rectifier to dcify the current. And some control circuitry. What does measurable resistance across the ac and dc sides indicate ? Should it not be open ? Did you throw a scope across the dc to see how much ac was on the battery side ?

That other thread about zincs in wood boats has me somewhat concerned ... if zincs protect the metal at the expense of the wood, ummm .... do they make kerosene vhf's ?

My understanding is that zincs protect more noble metal, bronze, even steel, at the expense of.........the zinc.

Re: The Harbor Master Called me Today

What I was taught a good pile of years ago was there are two types of corrosion, galvanic corrosion an stray current corrosion.

Galvanic corrosion is when you put two dis-similar metals in an electolyte (salt water), the more noble will be protected at the expense of the less noble (on the galvanic scale). Metals like copper an tin (what make up bronze) are fairly high on the chart and are therefore protected by ‘zincs’. Zinc is quite low on the chart.
This is why you don’t want to use brass fastenings, brass is an alloy of copper (high), and zinc (low). The zinc corrodes away and leaves a porous copper fastening.

I forget the details of stray current corrosion, but it typically is related to a problem with 120 or 240 volt shore power. If there is a problem with the shore power (on your boat, a boat in the area, or the power on the pier) that allows some AC current to ‘leak’ into the water it will cause all metals to corrode. Zincs do not protect against stray current corrosion, they can just sometimes be an indicator of a problem if they are corroding unusually fast. All the other metals will be suffering to.

on my battery charger, yes, it should have read as a complete open between the AC and DC sides, I had that reading of something like 365,000 ohms resistance (not open). I went no further on testing or diagnostics, just replaced it. .... It was 25+ years old, and had not been used in 27 years so I figured it was time anyway. Any reading from AC to DC is a problem.

Re: The Harbor Master Called me Today

If you have a positive and negative electrode in any electrolyte (salt
water) you get hydrogen gas from the negative cathode (protected metal) The
Hydrogen gas combined with the salt water makes Sodium Hydroxide or Caustic
Soda. Caustic Soda is used for pulping wood in the paper making process so
not good round the underwater metal on a wood hull.
There has to be a current and that requires a circuit. The current may come
from the ships battery's or it can come from the use of dissimilar metals
connected by bonding underwater. The circuit is completed through
the electrolyte.
You must never use brass or Manganese Bronze underwater as it is an alloy of copper and zinc.
(60 -40) the zinc migrates from the alloy leaving the copper like a porous
sponge. People use anodes to prevent this happening but that creates a more
serious problem " The degradation of the timber round the shaft log and bonded thru hulls.
Evidenced by white powder Caustic Soda being forced under huge pressure into
the boat and the surrounding timber. First thing you look for when buying a
wooden boat. Once it is there you really have to live with it, try and neutralize the Caustic Soda or do major surgery.
Unfortunately, there are less and less wood boats and stern gear is being made from Manganese bronze (brass) That's OK on a F/ glass boat you can use an anode but not on a wood boat if you expect it to last.
I understand not every one will agree with me. There have been warnings about this issue in Wooden Boat Magazine and The Professional Boat builder Magazine also Classic Boat Magazine. All parallel with my 60 odd year experience. Why do I write? I just feel so sad seeing sound wooden boats that should last for years being "Loved to Death" by their owners who think they are doing the right thing.
Please, Never use zinc or bonding on a wood boat!

Re: The Harbor Master Called me Today

I think the next order of business is replacing the cutlass bearing. To that end, I pulled off the prop nut, applied a little gentle heat to the prop, and gave it a tap or two to see if it wanted to come off.

It didn’t. So I need a prop puller.

Need a tool, make a tool. Right? I found a couple scraps of 1/2 inch aluminum plate that hopefully will be just the ticket.

Re: The Harbor Master Called me Today

Hi Jim,

you may get lucky but aluminum is not the ideal material, it tends to absorb shock rather than transfering it (the shock) to the parts to be seperated, anyway hope it works out for you.

Penetrating oil can help also, when under pressure (puller fully loaded), whack the hub (prop) with a hammer from the side at the same time holding a bigger hammer on the other side of the prop but only if you can avoid bashing the prop blades! If you have to use heat use an electric heatgun it`s not so destructive as flame!

Re: The Harbor Master Called me Today

you may get lucky but aluminum is not the ideal material, it tends to absorb shock rather than transfering it (the shock) to the parts to be seperated, anyway hope it works out for you.

Penetrating oil can help also, when under pressure (puller fully loaded), whack the hub (prop) with a hammer from the side at the same time holding a bigger hammer on the other side of the prop but only if you can avoid bashing the prop blades! If you have to use heat use an electric heatgun it`s not so destructive as flame!

Hope that helps,

Alan

You don't jar the aluminium. You pretension the puller then whack the jacking bolt to jar the shaft against the inertia of the prop. That should unload the aluminium.

It really is quite difficult to build an ugly wooden boat.
The power of the web: Anyone can post anything on the web
The weakness of the web: Anyone can post anything on the web.

Re: The Harbor Master Called me Today

I have almost identical bearing carriers on the boat I've run for a long time. Some years ago I pieced together a puller/pusher to change bearings, having tired of the shop charges to do so. I have pics, much better than trying to explain, I'll go dig around and try and find them for you. Essentially, hefty all-thread, the right nuts, washers and spacers, and away you go. Looking for pics now...

Re: The Harbor Master Called me Today

Just for future reference I’ll mention there is really no need for that center bolt. You just use the three corner bolts , and actually get three times the force with them as opposed to the one center.

Re: The Harbor Master Called me Today

Originally Posted by Boatsbgood

I have almost identical bearing carriers on the boat I've run for a long time. Some years ago I pieced together a puller/pusher to change bearings, having tired of the shop charges to do so. I have pics, much better than trying to explain, I'll go dig around and try and find them for you. Essentially, hefty all-thread, the right nuts, washers and spacers, and away you go. Looking for pics now...

Cool, looking forward to seeing the pictures. Do you get your bearings from a local shop or do you order them from someone?

Originally Posted by nedL

Uhmmm,....... Jim,..... I really like that first rate bonding wire from the bearing support to the skeg. Lol.

(which is it tying into the bonding? The bearing support or the skeg?

Truthfully, I have no idea what that wire is supposed to do. In this case it was a matter of letting sleeping dogs lay.

Originally Posted by nedL

Just for future reference I’ll mention there is really no need for that center bolt. You just use the three corner bolts , and actually get three times the force with them as opposed to the one center.

I agree, the center bolt isn't as useful for tightening the puller as the three through bolts are and in fact I didn't use it for tightening, but does keep the puller centered on the shaft in a similar way as the ring on your end plate.

Re: The Harbor Master Called me Today

HI Jim:
Attempting pics of bearing press..IMG_0732.jpgIMG_0708.jpg
Its mostly finding washers (or in one case a belt pulley) the right size to bear where you need, and then a tube that will clear the bearing. Double nuts at the small end and turn the other end. I've gotten bearings locally but mostly get em from portsupply. They're snug going in (remember to find the set screws before you start with the wrench on the end bolts). Generous never-seize or grease for assembly. Hope the pics post big enough to see...

Re: The Harbor Master Called me Today

I could certainly live with a boat like this....

How much does that dinghy weigh? Having that aft cockpit is a huge benefit for an extra room and on-top storage.
As to your water issue. Have you got a grill over the intake on the outside? I recall a similar instance where the alarms went off due to a plastic bag being sucked over the grill, but when the engine was shut down, the suction released and the bag drifted off, to be seen by the crew who was checking for water out the exhaust at the time.... Tescos if i recall.
Good luck with the bearing and bonding stuff, good to see stuff still going on.

Re: The Harbor Master Called me Today

Ahhhh, summer time. There is a grate on the raw water intake Ian. The dinghy weighs about 50 pounds/20 kilos~ish and can be a bit of a bear for one person to muscle up onto the roof. I’m thinking about building a swim step that it can live on when not in use.

Re: The Harbor Master Called me Today

Well, that took way longer than I thought it would. Got the stern gland pulled off and cleaned up. Then tried to press out the old cutlass bearing, but that sucker wouldn’t budge! Heat in combination with a few thousand pounds of pressure had not affect. I finally resorted to cutting the bearing in half to get it to move.

Re: The Harbor Master Called me Today

It’s hard to get excited about boat work in November, December, or January. The days are cold and dark, and getting darker, but then one day you realize that it’s not quite dark when you get home from work and the morage on the slip you’re not using comes due. All of a sudden, maybe, just maybe, it will be boat season again and working on the boat seems like something that might be a good idea. To which end, decided to pull a window out of the trunk cabin to re-bed.

Re: The Harbor Master Called me Today

It's definitely getting to be boat(work)ing season down here too. I know we still have a few months of cold weather ahead but the occasional nice day (like today) stirs the imagination toward summer and motivates progress. Nice to see Amazon getting some love!